A common method for testing modern microcircuits involves moving the tips of test probes into contact with selected test locations on the circuit. The probes are connected to test equipment for analyzing the performance of the circuit. During testing, certain circuit components may be altered. For example, with the probes in place on the circuit, laser trimming techniques may be employed to change the configuration of film resistor components of the circuit.
Typically, the probes are mounted to a rigid probe card that has a central opening through which the probe tips protrude. The probe card is carried by a fixture. A circuit is conveyed into the vicinity of the fixture and the fixture moves the probe card toward the circuit until the probe tips contact the circuit test locations. After the circuit is tested, the probe card is moved away from the circuit, and the tested circuit is replaced with another circuit for testing.
The prior art includes various test apparatus that employ mechanized movement of probes to and from a circuit that has been positioned near the test apparatus. These mechanisms, such as described in U.S. Pat. Nos. 3,996,517 (Fergason, et al.) and 3,787,768 (Kubota, et al.), generally achieve the task of moving the probes into contact with the circuit; however, heretofore available mechanisms lack the speed, precision and versatility required for high throughput circuit testing.